Initially the player may just be staving off imminent disaster as Cyric and his friends move quickly against the player - several strong deities against a relatively weak one. I could imagine the player being forced to abandon the Throne of Bhaal and going on the run across the planes. The player's goal would be to gain followers (faith=power), usurp the divine portfolio of another god, and carve out a base of power in the wider multiverse.

In the commens he clarifies that they were planning a reboot of the series:

…….It had been about 10 years since the BG games, which may have been too long for a direct sequel. I know we were planning a reboot of the series that could appeal to gamers unfamiliar with the franchise.

In a divine-level planar campaign, the player might stir up a civil war on Mount Celestia, conquer a layer of the Abyss, or assemble an adventuring party of divine avatars. Ultimately you’d take back the Throne of Bhaal, smack down Cyric and his friends, and establish a place for yourself among the pantheon of gods.

I'm glad they didn't end up going that route. It sounded like another high-level campaign similar to Throne of Bhaal. I didn't care for the gameplay as much once you reached very high levels in 2nd or 3rd Edition D&D.

Just give me a party of low-level adventurers with leather armor, thank you. You can keep the "divine-level" gameplay.